Furnace control



Nov. 23 1926. 1,607,764

CJ. LEHN FURNACE CONTROL Filed Sep'l'.. 24, 1923 2 Sheets-Sheet l i 53 52 ,60a w/ we f O l .Dull

Nov. 23 1926.

C. J. LEHN FURNAGE CONTROL Filed Sept. 24. 1925 2 Sheets-Sheet 2 Patented Nov. 23, lea-.a

UNITED STATES wie CHARLES J'. LEI-31N, 0F GAK PARK, LL-NOIS.

FURNACE CGNTBGL.

Application filed September 24, 1923. .Serial No. 854,356.

My invention relates to furnace controls, being more especially concerned with the control of the several furnaces constituting a battery, and also of furnaces having automatic fuel stokers. Certain phases of my invention, however, are not necessarily limited to these types.

One object f my invention is a control for a battery of furnaces such that the output rates of the several furnaces are brought from a low to a high rate, or vice versa, in successive order. Thus, certain of the furnaces are operated at a high rate of output-where they operate most eiiicientlywhile others are idle, merely preserving` their fires. As the demand on the battery increases, other furnaces are brought to this high Youtput rate in successive order as needed. This is in contradistinction to controls whereby all the several furnaces are operated simultaneously at the same intermediate rate determined by the demand on the battery. n

Another object of the invention is a dual control for the regulating` means of the individual furnaces of a battery, whereby either the demand on the output of the battery or the condition of the individual furnace controls the rateof the' respect-ive furnace. I thus obtain the advantage of being able to regulate the active functioning of a particular furnace by the demand on the battery and at the same time prevent the running of the furnace at an inefticiently high rate by a thermostat responsive to the temperature of flue gases in the furnace.

A further object of my invention is the joint control of a plurality of regulating means for the individual furnaces of a battery.

Many other objects, features and advantages of my invention will appear from the following description and claims. as well as from the accompanying drawings, in which Figure 1 is a front view showing diagrammatically a battery of furnaces provided with the furnace control of my invention;

Figure 2 is an enlarged side elevation of one of the furnaces of Figure 1;

Figure 8 is a detail view of t-he control unit of my invention;

Figure el is a fragmentary and diagrammatic elevation of one of the Stoker control mechanisms; and

Figure is a vertical section of one of the thermostats.

Similar characters of reference refer to similar parts throughout the several views.

As shown in Fig. 2, a plurality of furnaces 10a to 10e are grouped together to form a battery, .the boiler of each furnace supplying steam to a common steam header 11 extending along the rear of the furnaces. Each furnace 10 is provided with an automatic fuel stoker 12, here shown as being of the endless chain type. As shown in Fig. l, the chain grate 13 passes over a front sprocket la, the sprocket 1a being driven through a series of reduction gears 15 by a ratchet wheel 1G. with the ratchet wheel is pivoted at 18 to an actuating arm 19, one. end of which is pivoted to the shaft 20 of the ratchet wheel 16, while the free end of the arm 19 is provided with a slot 21. The arm 19 is oscillated periodically to advance the ratchet wheel 16 by an eccentric rod 22, the upper end of which encircles the large diameter of an eccentric 23 mounted upon a power shaft 23 extending the length of the battery. The stoker thus far described may be of any of the several suitable types now in use, the details of the stoker itself forming no part of my invention. Y

1n lieu of the usual clamping means for securing the free end of the accentric rod 22 to the arm 19 at one of its adjusted positions, 1 provide an automatic means for adjusting the leverage of the eccentric rod upon the actuating arm 19, this means comprising a. link 24 connecting the pin 25, which pivots the end of the rod 22 in the slot 21, with a diaphragm-actuated lever 26. rllhe lower end of the lever 26 is pivoted to the customary frame of a diaphragm control mechanism 27, the diaphragm `28 of which is connected to the lever 26 adjacent its fixed pivot to provide a relatively long movement for the link 24, as will later be explained. Air under pressure is led by the tube 29 to one side of the diaphragm 28. A tension springl 30 is provided which normally urges the lever 26 to balance'the pressure of the air against the diaphragm. This balancing spring tension may be varied by means of a plurality of holes 31 at the upper end of the lever 26. 1t is clear that an increased air pressure against the diaphragm 28 will swing the pivot pin 25 of the eccentric rod outwardly in the slot 21. so that the reciprocating movement imparted by the eccentric 23 will lessen the number of The pawl 17 which cooperates 7 teeth advanced with each reeiprocation by the pawl 17, while a lessening of the air pressure against the diaphragm 28 will, conversely, increase the advancing of the ratchet wheel 16, and, consequently, feed new fuel along the chain grate at a faster rate, resulting in a more intense fire, and, consequently, greater steam output from the boiler.

Air under pressure is supplied to the tube 29 through a vertical branch pipe 32 communicating with a supply pipe 33 extending across the front of the furnaces from an air tank 34. The air pressure in the tank 34 may be kept constant by means of a pressure reducing valve 35 in a feed pipe 36 leading from any suitable source of air under pressure.

From the branch pipe 32 a transverse pipe 37 leads to the rear of each furnace and communicates with a thermostat 38 at the top of the furnace and with a diaphragm mechanism 39. This diaphragm unit, which is similar to the diaphragm mechanism 27 associated with each of the Stoker controls, opens and closes a damper 40 for cont-rolling the escape of flue gases from the particular furnace to the breeching 41 extending the length of the battery. As shown in Fig. 2, an increase in air pressure against the diaphragm of the unit 39 will lift the lever 42 on its fixed pivot 43, allowing a counterweight 44 'to pull a cable 45 around a sheave 46, the latter being secured to the shaft of the damper 40. Increased pressure in the line 87 thus closes the damper 40, checking the fire of the furnace, while a lessening of the pressure in the line 37 vopens the damper to provide more draft for the particular furnace.

Leading from the respective branch pipes 32 of the several furnaces 10a-l0e are a plurality of tubes 47-47e, respectively, extending to the control box 48 shown in Fig. 3. From the steam header l1 a small steam pressure pipe 49 also extends to the control box 48 communicating with the fluid pressure side of a diaphragm device 50, which works against the pressure o-f a spring 5l to raise the short lever arm of a control lever 52 having a fixed pivot at 53 on a suitable bracket. At the opposite side of the box 48 a bracket 54 provides a guide- Way for the free end of the lever 52, a second lever 55 also being pivoted at 56 on the bracket 54 and connected to the free end vof the control lever 52 by a link 57. The respective tubes 47h-4"e lead to terminal stems 58a--58e secured in spaced relation to a bracket 59. In that portion of the bracket 59 shown as overhangingthese terminals a plurality of valve rods 60a 60e are reciprocably mounted so that their heads may contact the open ends of the respective stems 58a58e to close atmospheric relief for the several tubes. rEhe upper end of each valve rod GOM-430@ extends through an aperture in the second lever 55 and is provided thereabove with a nut and lock nut 6l. rlhese nuts are so adj usted on the several rods that when 'the second lever 55 is lift d about its fixed pivot 56, the valve rod 60 will be lifted from its mating valve seat or terminal stem 5S;L and, with continued raising of the lever, the valve rod 501 v'll next be raised from its cooperating stem 5S" and so on until finally the rod 60 is lifted from the terminal 586. ln this way the tubes 4721 7e are relieved to atmosphere in successive order, the number of tubes thus being relieved to atmosphere being depen-dent upon the steam pressure conveyed to the diaphragm 50. lecause of the combination of leverages employed, it will be seen that a very slight iiuctuation in the steam pressure against the diaphragm will result in considerable movement of the free end of the second lever which lifts the valves from the valve seats or terminals of the tubes 57 a4379.

llilhen the engine 62, which the steam header il is here shown as supplying, is required to be operated ata greater' rate, the pressure of steam in the header ll, of course, falls. This slightly lessens the pressure against the diaphragm 50, thus raising the free end of the operatino` lever 52 and in turn the second lever nere shown as just beginning to raise the valve C from its mating terminal 58C to relieve the tube 47. The pressure in the air lines 87 and 29 of the particular furnace 10C is likewise reduced, allowing the spring 30 to pull against the stoker control diaphragm 28 drawing the eccentric rod 22 toward the pivot of the arm 19 to increase the feed of the stoker. At the same time the lessening the pressure in the line 37 permits the lever 42 of the damper control diaphragm device 39 to swing downwardly, opening the damper 40 to increase the furnace draft.

il is ess not onlj.v ie increase the fire of a. cular rv:ce to its n'iost etlicient n the demand the l ttery as a o provide means fnrnace so that nei rl boilers.

ont.

l temperature 't the rnace fornis an exthe e p arres-pensive to llt) of the branch air lines the temperature of such combustion gases. As shown in detailin Fig. 5, the thermostat is mounted in the side of a furnace, being supported by a fran'le 63 having a rearwardly extending boss (ill into which is threaded the outer end of a metal-tube which eX- tends inwardly and across the path of the escaping flue gases. At the inner end of the tube 65 a cap 68 is secured which centers a glass rod 67 (or other rod having a coeliicient of expansion considerably less than that of the metal of the tube 65), The outer end of the glass rod protrudes through theframe 63 and is engaged by the end of the adjustable screw 68. The screw 68 is supported in a downwardly extending lever G9, the pivot of the lever being provided for in its upper `end by a short strip of spring steel 70 clamped on the frame 63. My purpose in providing such a pivot arrangement is to prevent any lost motion for the lever 69. The lower end of the lever 69 is provided with another adjustable screw 7l, the endof which acts as a closure for the terminal fitting 72 of an air line 73 which, as shown in Fig. 2, communicates with the rearwardly extending air linel?. A weight 69 `is attached to the lower end of the lever 69 and the mass of the weight is spaced vertically from the pivot strip 70 sufficiently so that gravity will tend to swing the lever 69 inwardly at all times keeping a pressure against the glass rod 67. l/Vhen a particular furnace has been brought to too high a temperature for efficiency, the heat of the escaping gases will expand the metal tube G5 of the thermostat considerably faster than the glass rod 67 expands, allowing the lever 69 to be swung inwardly so that the end of the screw 7l closes the terminal of the air line 73. This, it obvious, results in an increased pressure on the diaphragm of the control device 39, resulting in a closing'of the damper A l0 to check the fire. The increased air pressure also actuates the stolzer control diaphragm 28 to decrease the Stoker speed. wWhen the lire has been sufiiciently checked, the thermostat will again relieve the air line 73, opening the draft and increasing the stolzer feed.

In order to secure the most advantageous operation and sensitiveuess ofthe control system, a. needle valve 74 is provided in each 32 so that the dow of compressed air into the system of each particular furnace control will cooperate with the rate of relief provided for the apertures of the lseveral relief terminals.

In order to establish a proper balance of pressures as between the stoker control and the damper control. I also provide a needle valve 75 in the air line leading to each (lampe Veen-trol diaphragm device 39.

Because of the great sensitiveness of the in the steam pressure, the closing of a particular terminal 58h-58 will provide more than merely onand off positions, for, espe-v cially when high air pressure is employed in the system, the lifting of a particular valve rod (5060O will have somewhat t-he effect of a needle valve during the first few thousandths of an inch of movement, so that intermediate positions of the respective dampers Ll0 and stoker regulators will be obtained. ln this way the control system will quickly bring itself to a balance rather th an a frequent alternation between a hot fire and a slow fire in one of the 'furnaces.

I have also shown my control system as including the regulation of a forced draft for each of the furnaces of the battery. As shown in the drawings, each furnace is provided with an individual forced draft by means of a blower 76 driven by an individual steam turbine 77. A steam pipe 78 extends from the steam header 11 beneath the battery of furnaces and supplies each turbine '77 `with steam for its operation. In the passage between the common steam line T8 and each individual turbine is inserted a regulating valve 79 controlled by a diaphragm device communicating with the air line system of the respective furnace. Thus, when the air line of a furnace is relieved, due to a falling inthe common steam pressure, the regulating valve 79 is permitted to open farther. admitting more steam to the `turbine 77, increasing the forced draft. Conversely when the air pressure in the control i tem for the respective furnaces is closed, the increased pressure in the line will din'iinish the steam supply to the tur bine and decrease the forced draft.

if provide cutoff valves 80-80 in the air pipes of each furnace control system whereby any of the several devices may be rendered inoperative, if desired. lVhen it is desired to maire repairs in one of the furnaces, or for other reason to drop it out of alf-tive service in the battery, the control for that furnace may be rendered inoperative by closing the valve 81 in the branch pipe 32.

,rlthough I have illustrated and described but one elnoodiment of my invention, it is to be understood, of course, that its application is not thus limited and that many changes may be made without departing from the scope or spirit of my invention.

l claim:

l. The combination with a battery of furnaces, of means controlled by fluctuations inv the demand on said battery for changing the output of successive furnaces of said battery between operatingl conditions of low and of high output, said means including regulatmeans for controlling the respective inoividnal furnaces in response to their temperatures.

lilo

2. The combination of a plurality of furnaces supplying a common demand, each of said furnaces normally operating at low output. means responsive to said demand for bringi thel operation of said several; furnacesto liigheil output in successive order, and means responsive tothe ten'iperatures of the individual furnaces for controlling them respectively.

23. The combination of a plurality of furnacesv supplyingl a common demand, each of said furnaces normally operating at loW output', means responsive to said demand for bringing the operation of. said several furnaces to a higher output in 'successive order, and means responsive to the temperatures of said individual furnaces for controlling the output of the respective furnaces.

d. rEhe combination of a. plurality oi' boiler furnaces furnishing steam to a common supply, fuel feed means for each of saidv furnaces, a plurality of control means, in association respectively with each of saidv feed nieans, for varying in successive order the rates of such fuel feeds in said several furnaces, said control means being responsive to the pressure of said common steam supply, and also to the conditions of the respective individual furnaces.

5. The combination of a plurality of boiler furnaces furnishing steam to a common supply, fuel feed means for each of said furnaces, a plurality of control means for varying in successive order the rates of suchA fuel feeds in said several furnaces, said control means being responsive to the pressure of said common steam supply and also to the temperatures of the individual furnaces.

6. The combination of a plurality of boiler furnaces furnishing steam to a common supply, fuel feed means for each of said furnaces, and means controlled by said common steam supply and by the temperature of the iiue gases in each furnace for regulating said fuel feed means.

't'. The combination of a plurality of boiler furnaces furnishing steam to a common supply, regulating means for each of said furnaces, and means controlled either by said common steam supply or the temperature of combustion gases in said furnace for operating said several regulating means in successive order.

8. The combination with a plurality of furnaces contributing to a common output. of fuel feed regulating devices for each of said furnaces, each such devices being controlled in response either to said common output or to the temperature of the respective furnaces.

The combination with a battery of furnaces furnishing a. heated article to aV common supply, of a fuel feed regulator for each of said furnaces, each said regulator being controlled Veither by the condition; of said supply or by the condition of its associated furnace.

i0. The combination of a plurality of furnaces contributing to a common supply, fuel feed nie-ans for each of said furnaces, said feed means being controlled by either the temperature of their respective said furnaces or said common supply.r

l1. The combination with a plurality of boiler furnaces furnishing steam for a coinmon supply, of fuel feed regulating means foi' each of said furnaces, said regulating means being controlled either by saidl common steam supply or by. the temperature of l flue gases in the respective furnaces.

l2. The combination of a plural-ity of boiler furnaces furnishing steamA to a common s-upply, individual regulating means for each of said furnaces, a fluid pressure line for each of said regulating means, a diaphragm in. each of said lines for varying the respective said regulating means, a control valve in each of said lines responsive to said common steam supply, and a second control valve in each of said lines responsive to the temperature of flue gases in the rcspective furnaces.

13. The combination with a battery of furnaces, each.A of said furnaces contributing to a joint output, individual rdiaphragm operated meansassociated with each of said fui'- naces for regulating the fire in such respective furnace, fluid under pressure for actuatingv said diaphragm, a pair of control valves communicating with each of said diaphragmsfor controlling such diaphragm, one of said pair being responsive to the temperature of the said respective furnace and the other of said pair being responsive to said joint output.

14. In combination with a battery of furnaces, each of which contributes to a joint output, individual diaphragm-operated means associated With each of said furnaces for regulating the fuel combustion in such respective furnace, a Huid pressure line for operating each said diaphragm, a source of fluid under pressure for supplying said line, and relief means for each said pressure line, each said means being responsive to either said joint output or to the temperature of the respective furnaces.

v15. In combination With a battery of boiler furnaces for supplying a common steam demand, a fuel stolzer for each ofsaid furnaces, a fluid pressure operated regulator for each said Stoker, two valves for each said regulator, either of which valves controls suchv fluid pressure of said regulator, one of said two valves being responsive to the temperature of combustion gases in the respective furnace While the other of said tivo valves is responsive to said common demand.

lOl.)

16, The combination of a plurality of furneces for n common supply, individual blowers for each of said furnaces adapted to supply forced draft thereto, separate drivw 5 ing means for each of said blowers, and a regulating device for cachot said Jfurnaces, sind regulating devices being controlled by the temperature of their respective furnaces and by said common supply and being,l adapted to control the operation of said blower driving means.

ln witness whereof, I hereunto subscribe my name this l2th day of September, 1923.

CHARLES J. LEHN. 

